valid-xhtml10.png size

http://www.w3.org/Icons/valid-xhtml10.png 2 414 bytes
http://www.w3.org/Icons/valid-xhtml10.gif 2 345 bytes

How comes the png is larger?
Did a quick run through pngout and it produced a 1988 bytes large png.
That's 18% smaller. Maybe not very much, but why waste bandwidth?

/Vaste